Currently Being ModeratedSep 28, 2013 7:59 PM (in response to Jonathan Foster Kenny)
iAd Workbench is currently available to promote apps in the U.S. App Store. Campaigns created using iAd Workbench run on iAd's U.S. App Network. Developers interested in advertising outside of the U.S. should submit a request and a representative will contact you.
I'm in the same case. I submit a request and I get this answer from apple:
"Thank you for your interest in the iAd platform.
I would be more than happy to discuss promoting your applications. Please could you let me know more about your application? What it does, the cost etc?"
I've answered providing that information 1 month ago and I'm still waiting for an answer.
It seems actually it isn't possible to promote an app outside of the U.S.